Properties of Minerals

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Vocabulary

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mineral - a naturally occurring ,inorganic solid that has a crystal structure and a definite chemical composition.
inorganic - not formed from living things or the remains of living things
crystal-a solid in which the atoms are arranged in a pattern that repeats again and again
element -a substance composed of a single kind of atom
compound -a substance in which two or more elements are chemical joined
Mohs hardness scale - a scale raking ten minerals from softest to hardest;used in testing the hardest of minerals
streak -the color of a mineral's powder
luster -the way the mineral reflects light from its surface
cleavage -a minerals ability to split easily along flat surfaces
fracture -the way the minerals looks when it breaks apart in an irregular way
fluorescence-the property of a mineral in which the mineral glows under ultraviolet

Outline

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• What is a mineral?
  • A mineral is a naturally occurring, inorganic, solid, that has a definate chemical composition and a crystal structure.These are the different properties used to identify a mineral.

• Naturally Occurring
  • In order to be classified as a mineral it must be naturally occurring.This means a substance is not manufactured by people.

• Inorganic
  • To be classified as a mineral a substancemust also be inorganic.The substance cannot come from the remains of living things like coal.

• Solid
  • A mineral is always a solid with a definite volume and shape.This means that the particles in a mineral are tightly packed together, so that they cannot move.But in a liqui, the particles flow around freely.A solid keeps its shape becausa its particles can't flow freely.

• Crystal Structure
  • A mineral's particles line up in a repeating pattern, to form a solid called a crystal.The crystal structure, is sometimes obvious from a mineral's appearance.However,in other mineral's, its crystal structure is only visible through a microscope.

• Definite Chemical Composition
  • This is one of the properties a mineral must have in order to be considered as a mineral.Having a definite chemical composition meansthat a mineral always contains certain element in definite proportions. Elements are composed of a single kind of atom, while compounds are two or more elements combined.All the atoms of the same element have the same chemical and physical properties. Once the elements are combined together to create compounds, the elements no longer have distinct properties.

This image shows a compound called cinnabar which is made out of the elements mercury and sulfur.

Identifying Minerals

• Each mineral has its own specific properties that can be used to identify it.

• Hardness
  • Hardness is just one of the eight properties that are used to identify a mineral.A mineral expert named Friedrich Mohs invented a test to describe the hardness of amineral in 1812.This test is called the MOHS HARDNESS SCALE and it ranks ten minerals from hardest to softest.Friedrich Mohs's test uses a fingernail, a cooper penny, a steel knife,and a window glass to figure out the hardness of the mineral.

• Color
  • Although the color of a mineral is an easily identified ,it alone can't be used to identyfi a mineral.This is because only a few minerals have their characteristic color.But other minerals like quartz come in many different colors.

• Streak
  • The color of a minerals powder is its streak.

• Luster
  • The way a mineral reflects light from its surface is called luster.Checking the luster of a mineral is another simple test used to identify the mineral.

• Density
  • Density is the mass in a given space.

• Crystal Systems

• Cleavage and Fracture

• Special Properties